Reciprocating piston internal combustion engines have been known for many years. An operating fundamental common to internal combustion engines of the reciprocating piston type is that the reciprocal motion of the pistons must be translated into rotary motion of a crankshaft. This has been achieved most conventionally through a connecting rod attached to each piston at one end through a wrist pin and rotatably mounted to an offset crank arm of the crankshaft at an opposite end.
Other arrangements for converting the reciprocal motion of the piston into rotary motion of a crankshaft have also been proposed. For example, it has been proposed to utilize an elongated internally toothed roller gear attached to a piston and moved to maintain engagement of the teeth with a crankshaft drive gear to impart rotation thereto. Examples of such arrangements are shown in U.S. Pat. Nos. 1,687,744, 4,608,951 and 4,395,977. Such arrangements have heretofore not achieved wide spread commercial acceptability.
Opposed cylinder internal combustion engines are also known. In such engines, dual pistons are fixed to a common yoke structure or connecting rod arrangement and the pistons are reciprocated within opposed cylinders. Reciprocal motion of the pistons is conventionally translated into rotary motion by an offset crank pin of a crankshaft. U.S. Pat. Nos. 2,172,670 and 2,122,676 disclose engine designs wherein opposed pistons are connected by a connecting rod arrangement. U.S. Pat. No. 4,485,768 discloses a common yoke type internal combustion engine as described and further includes means for altering the stroke and compression ratio of the engine. Specifically, this is achieved by altering the orbital path of a coaxial crank pin and slider relative to a crankshaft axis.